Rapid method for determining nitrogen in tantalum and niobium alloys

Adaptation of commercial instrument which measures nitrogen and oxygen in steel gave results in less than four minutes. Sample is heated in helium atmosphere in single-use graphite crucible. Platinum flux facilitates melting of sample. Released gases are separated chromatographically and measured in thermal-conductivity cell

Burst diaphragm flow initiator Patent

Burst diaphragm flow initiator for installation in short duration wind tunnel

Short-duration, transonic flow, variable-porosity test section

Short-duration test facility obtains extremely high Reynolds number flows in subsonic, transonic, and supersonic speed ranges, and aids in solving Reynolds number-dependent aerodynamic and thermodynamic problems in design and testing of large, high speed vehicles. The modified blowdown wind tunnel avoids data confusion and aerodynamic noise

Procedure for rapid determination of nickel, cobalt, and chromium in airborne particulate samples

A rapid, selective procedure for the determination of 1 to 20 micrograms of nickel, chromium, and cobalt in airborne particulates is described. The method utilizes the combined techniques of low temperature ashing and atomic absorption spectroscopy. The airborne particulates are collected on analytical filter paper. The filter papers are ashed, and the residues are dissolved in hydrochloric acid. Nickel, chromium, and cobalt are determined directly with good precision and accuracy by means of atomic absorption. The effects of flame type, burner height, slit width, and lamp current on the atomic absorption measurements are reported

C.V.D. annual report: November 1965 research project RU27-1 :an analogue method for the determination of potential distributions in semiconductor systems

A general method for the solution of the nonlinear Shockley-Poisson differential equation which governs the potential distribution in non-degenerate semiconductor systems is described which can be applied to the evaluation of depletion layer widths, carrier densities and capacitance bias relationships of p-n junction structures. The method is based upon the use of a particular type of resistance network analogue and results obtained for several one and two dimensional configurations are discussed

Analysis of potential helicopter vibration reduction concepts

Results of analytical investigations to develop, understand, and evaluate potential helicopter vibration reduction concepts are presented in the following areas: identification of the fundamental sources of vibratory loads, blade design for low vibration, application of design optimization techniques, active higher harmonic control, blade appended aeromechanical devices, and the prediction of vibratory airloads. Primary sources of vibration are identified for a selected four-bladed articulated rotor operating in high speed level flight. The application of analytical design procedures and optimization techniques are shown to have the potential for establishing reduced vibration blade designs through variations in blade mass and stiffness distributions, and chordwise center-of-gravity location

Comparison of inert-gas-fusion and modified Kjeldahl techniques for determination of nitrogen in niobium alloys

This report compares results obtained for the determination of nitrogen in a selected group of niobium-base alloys by the inert-gas-fusion and the Kjeldahl procedures. In the inert-gas-fusion procedure the sample is heated to approximately 2700 C in a helium atmosphere in a single-use graphite crucible. A platinum flux is used to facilitate melting of the sample. The Kjeldahl method consisted of a rapid decomposition with a mixture of hydrofluoric acid, phosphoric acid, and potassium chromate; distillation in the presence of sodium hydroxide; and highly sensitive spectrophotometry with nitroprusside-catalyzed indophenol. In the 30- to 80-ppm range, the relative standard deviation was 5 to 7 percent for the inert-gas-fusion procedure and 2 to 8 percent for the Kjeldahl procedure. The agreement of the nitrogen results obtained by the two techniques is considered satisfactory

Electrostatic forming and testing of polymer films on a 16-foot diameter test fixture

The large space systems technology program investigated different forms of large, lightweight, deployable structures which could be carried on the Space Shuttle. Different forms and concepts of antennas as a type of large space system were investigated. The electrostatically controlled membrane reflector made of metallized material concept was chosen. The concept is a good candidate for creating an antenna with high surface quality and has the ability to be packaged and deployed from the Shuttle with a significant reduction in weight compared to other antenna types

Quantum kinetic theory VII: The influence of vapor dynamics on condensate growth

We extend earlier models of the growth of a Bose-Einstein condensate to include the full dynamical effects of the thermal cloud by numerically solving a modified quantum Boltzmann equation. We determine the regime in which the assumptions of the simple model are a reasonable approximation, and compare our new results with those that were earlier compared with experimental data. We find good agreement with our earlier modelling, except at higher condensate fractions, for which a significant speedup is found. We also investigate the effect of temperature on condensate growth, and find that this has a surprisingly small effect. The discrepancy between theory and experiment remains, since the speedup found in these computations does not occur in the parameter regime specified in the the experiment.Comment: Fourteen pages, TeX source with 11 figures. Changes : Extended section on formalism to include a derivation of the ergodic Boltzmann equation that we use, and a fuller explanation of the numerical methods. Explained more fully the possible errors with the experimental data. Added section detailing the source of possible errors in this formulation. Added comparison of our work with the manuscript cond-mat/0001323, and some analysis of the fits to the MIT growth curve

Documenting helicopter operations from an energy standpoint

Results are presented of a study of the relative and absolute energy consumption of helicopters, including limited comparisons with fixed-wing aircraft, and selected surface transportation vehicles. Additional comparisons were made to determine the level of reduction in energy consumption expected from the application of advanced technologies to the helicopter design and sizing process. It was found that improvements in helicopter consumption characteristics can be accomplished through the utilization of advanced technology to reduce drag, structures weight, and powerplant fuel consumption